Re: B345 Shoal Draft Performance
If you're not into racing, or not already accustomed to the upwind effectiveness of a deep fin keel, then I doubt you'd notice any significant detriment with a shoal keel.
The 20 second PHRF difference, if correct, is significant, but again, if you're not racing....
I suspect you'll be plenty impressed with the increase in performance and handling over your SC31, even with the shoal keel option, though along with the speed you may experience a bit more tenderness than you're used to.
It will be quite a transition...
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"